Fedora Release Life Cycle

From FedoraProject

The Fedora Project releases a new version of Fedora approximately every 6 months and provides updated packages (maintenance) to these releases for approximately 13 months. This allows users to "skip a release" while still being able to always have a system that is still receiving updates.

Development Schedule

We say approximately every 6 months because like many things, they don't always go exactly as planned. The schedule is not strictly time-based, but a hybrid of time and quality. The milestone releases are tested for compliance with the Fedora Release Criteria, and releases will be delayed if this is not the case.

The schedule for the release currently under development, Fedora 22, is on its release schedule page. Alpha, Beta, and General Availability (final) releases happen at 10:00am Eastern US Time, which is either 1500UTC or 1400UTC depending on whether or not daylight savings is in effect.

Development Process

Fedora uses a system involving two 'development' trees. Rawhide is a constantly rolling development tree. No releases are built directly from Rawhide. 14 weeks before the planned date of a Fedora release, a tree for that release is "Branched" from the Rawhide tree. At that point the Rawhide tree is moving towards the release after the new Branched release, and the pending release is stabilized in the Branched tree.

Birth of a FedoraThis means that development of a Fedora release is considered to begin at the time its predecessor branches from Rawhide. For instance, development on Fedora 22 began the day after Fedora 21 branched from Rawhide and entered the stabilization process.

After the Bodhi enabling point, the Bodhi system is permanently active on the Branched release (all the way until it goes EOL), and requirements for updates to be marked as stable are set out in the Updates Policy. Packages must go through the updates-testing repository for the release before entering its stable repository, according to rules defined in the updates policy: these rules tighten gradually from Alpha through to post-GA (Final), but the basic process does not change.

For some time prior to a milestone (Alpha, Beta, Final) release a freeze is in effect which prevents packages moving from updates-testing to stable except in accordance with the blocker and freeze exception bug policies. This freeze is lifted once the milestone is finished, and so packages begin to move from updates-testing to stable as normal again, until the next milestone's freeze date.

Schedule Methodology

Fedora release schedules are proposed by the Fedora Program Manager and ratified by the Fedora Engineering Steering Committee (FESCo), with input from other groups. FESCo is responsible for overseeing the technical direction of the Fedora distribution. A core schedule is created using the key tasks listed below. Detailed team schedules are built around these dates.

The time before the change proposal checkpoint/deadline and after the Branch point of the previous release is the time dedicated to development

Development time varies from from release to release based on when the previous release branched

The stabilization and testing time (from Branch point until GA release) is held constant from release to release

Schedule draft is submitted to FESCo via it's ticketing system for the approval. Initially, all milestones except "Change Checkpoint: Proposal submission deadline (System Wide Changes)" are scheduled as so called "no earlier than". Final schedule is set after the FESCo's review of proposed and accepted Changes proposals and "no earlier than" note is removed from schedule. This gives us opportunity to properly plan release, especially for changes with high impact on the release.

Development Schedule Rationale

Fedora generally develops new releases over a six month period to provide a regular and predictable release schedule. The bi-annual targeted release dates are May Day (May 1st) and Halloween (October 31) making them easy to remember and avoiding significant holiday breaks. Changes to this standard must be approved by the community-elected Fedora Engineering Steering Committee (FESCo).

A six month release schedule also follows the precedence of Red Hat Linux (precursor to Fedora). Former Red Hat software engineer Havoc Pennington offers a historical perspective here. GNOME started following a time based release based on the ideas and success of Red Hat Linux and other distributions following Fedora having adopted a similar release cycle. Several other major components, including the Linux kernel, Openoffice.org, Xorg, have started following a time based release schedule. While the exact release schedules vary between these components and other upstream projects, the interactions between these components and Fedora makes a six month time based release schedule a good balance.

Although due to how planning process and release validation works, Fedora is not a strictly time based distribution but uses combination of both time and feature based release paradigms. This way we can react to bigger changes aka new installed, way how we release bits (Fedora.Next) etc.

Schedule Contingency Planning

If the Alpha, Beta, or Final Go_No_Go_Meetings result in a "No Go" determination, that milestone and subsequent milestones will be pushed back by one week.

One week is added to the schedule to maintain the practice of releasing on Tuesdays. Tuesdays are the designated release day because they are good days for news coverage and the established day we synchronize our content with the mirrors that carry our releases. Be aware of holidays and of possible PR conflicts (contact Fedora PR) with the new proposed final date.

Maintenance Schedule

We say maintained for approximately 13 months because the supported period for releases is dependent on the date the release under development goes final. As a result, Release X is supported until one month after the release of Release X+2.

This translates into:

Fedora 20 will be maintained until 1 month after the release of Fedora 22.

Fedora 21 will be maintained until 1 month after the release of Fedora 23.

Maintenance Schedule Rationale

Fedora is focused on free and open source software innovations and moves quickly. If you want a distribution that moves slower but has a longer lifecycle, Red Hat Enterprise Linux, which is derivative of Fedora or free rebuilds of that such as CentOS might be more suitable for you. Refer to the RHEL page for more details.

Historically, the Fedora Project has found supporting two releases plus Rawhide and the pre-release Branched code to be a manageable work load.

End of Life (EOL)

When a release reaches the point where it is no longer supported nor updates are created for it, then it is considered End of Life (EOL). Branches for new packages in the SCM are not allowed for distribution X after the Fedora X+2 release and new builds are no longer allowed.